The awnser is simple, a special sentry would use a special wrench (Like the Gunslinger), which would act as a Wrangler. It would make the Wrangler redundant, but anyone with half a brain would use something else.

use gunslinger ..

Right click with a new wrench that is also used to make this sentry, from my point of view this is the most simple and best option.

ok. but can it come with the box

come with The Mobile Sentry Gun and the wrench of free.???? plz

He could have a new PDA that lets the player build this, and with the PDA equipped, maybe the Special Attack button (the one used to change vaccinator's resistance type) could be used to move this beast.

special wrench to set way point to control the base while the gun is on auto fire and posibly wragler controls gun while some one else controlse the base with the wrench

引用自 Jar Jar Binks：

He could have a new PDA that lets the player build this, and with the PDA equipped, maybe the Special Attack button (the one used to change vaccinator's resistance type) could be used to move this beast.

Well since Valve recently added +attack3 for the medic to use the Vaccinator's resistance types, why not?

The only problem that a new PDA would have is if you have the gunslinger + this. Either the gunslinger would have to be changed when combined to compensate (or changed overall altogether) or the gunslinger's sentry take priority (that is, have a mini-sentry anytime the gunslinger is equipped).